“And if you were to eat steak at the computer, you’d probably drop some on the floor.”

“I don’t know about that…”

“Dude, I’ve seen you eat.” Yes, the dog calls me “dude.” There may be obedience classes in her future.

“All right, we’ll allow the possibility.”

“Therefore, it’s possible that you dropped steak on the floor. And according to Everett’s Many Worlds Interpretation of quantum mechanics, that means that you did drop steak on the floor. Which means I just need to find it.”

“Well, technically, what the Many Worlds interpreation says is that there’s some branch of the unitarily evolving wavefunction of the universe in which I dropped steak on the floor.”

“Right, so I just need to find the unitary whatsis.”

“The thing is, though, we can only perceive one branch of the wavefunction.”

“Maybe you can only perceive one branch. I have a very good nose. I can sniff into extra dimensions.”

“That would explain some of your mystery barking fits, but extra dimensions are a completely different thing. In this case, once there has been sufficient decoherence between the branches of the wavefunction that there’s no possibility of interference between the different parts, they’re effectively separate and inaccessible universes.”

“What do you mean, decoherence?”

“Well, say I did have a piece of steak here– stop wagging your tail, it’s a hypothetical– quantum mechanics says that if I dropped it on the floor, then picked it back up, there could be an interference between the wavefunction describing the bit of steak that fell and the wavefunction describing the bit of steak that didn’t fall. Because, of course, there’s only a probability that I’d drop it, so you need both bits.”

“What would that mean?”

“Well, the steak would probably produce some sort of interference pattern. I’m not really sure what that would look like. The point is, though, it doesn’t really matter. The steak is constantly interacting with its environment– the air, the desk, the floor–“

“The dog!”

“Whatever. Those interactions are essentially random, and unmeasured. These interactions lead to shifts in the wavefunctions of the different bits of steak, and those shifts make it so the wavefunctions don’t interfere cleanly any more. That process is called ‘decoherence,’ and it happens very fast.”

“How fast?” she asks, looking hopeful.

“It depends on the exact situation, but as a rough guess, I’d say about the same time as the lifetime of a bunny made of cheese. 10-30 seconds or less.”

“Oh.” She deflates a little. “That’s fast.” She still hasn’t caught a bunny made of cheese.

“Yeah. And once that decoherence has happened, the different branches of the wavefunction can’t really interact with each other any more. Which means, essentially, that the different branches become separate universes that are completely inaccessible to one another. Things that happen in these other ‘universes’ have absolutely no effect on what happens in our universe.”

“Why do we only see one branch of the whatchamacallit?”

“Ah, now that’s the big question. Nobody knows. A lot of people think this means that quantum mechanics is fundamentally incomplete, and there’s a whole community of scientists doing research into the fundamentals of quantum theory, and the various interpretations. Matt Leifer has a whole blog talking about this stuff.”

Comments

I suppose you’ve changed that old Einstein quip about explaining things to your grandmother into explaining them to your dog. Your dog seems to have fantastic physics and speaking abilities, much greater than any other dog I’ve met.

Well, that was before I knew she was an expert on quantum foundations, or at least had about as good a grip on them as the majority of physicists :)

To clarify, I have nothing against dogs in general, just the concept of writing posts about them when they are not either discussing physics or being captioned in an amusing way. In any case, they don’t allow pets in my apartment building, so my dog related posts would be rather boring.

ok, considering I was on my way to bed and considering I have had three glasses of wine, I was very amused. Enough to actually follow the text and the gist and not get brain farts or stare blankly into the ether nor did I lose track. I have to say, I loved this piece (coming from my interest in …wait now…brain fart..have to scroll up…right: quantum physics/mechanics..) and having my own menagerie of cats who like to knead private parts of the body and lay on the warm bits, I did not see anything weird about the crotch shot. Keep up the great writing. Laurie

Dogs are pack animals. They are instinctively built for constant company, not to mention constant activity. Life among humans denies them this for the greater part of each day, causing them stress/distress. Barking is one method of relieving this stress. It is such a common symptom that we have come to expect it of dogs.

I live in a universe where I always eat at my computer desk, I always have steak on Friday, I usually drop a bit of steak on the floor every Friday, and I don’t own a dog but the cat won’t eat anything but catfood… So it goes…

I live in a universe where I always eat at my computer desk, I always have steak on Friday, I usually drop a bit of steak on the floor every Friday, and I don’t own a dog but the cat won’t eat anything but catfood… So it goes…

I reside in a time warp with two rescued dogs of mix breeding who apparently not only know physics but in their own way, they’ve been trying to teach me…they lose patience with me as I’m too dumb to comprehend their teachings and the subject matter, and I’m sure they use this computer when I’m not around… so much for higher human education..dogs 1, human 0.

Love this. Make me think of my brother in-law who is a true life quantum professor. But he’s also a vegetarian, and israeli… and like most tremendous science minds out there, doesn’t have much sense of humor. All that said, I laughed out loud reading this.

Kudos to the very clever Dr. George Hockney, quantum computing expert, who figured out my dialogue, and emailed me as below.

===========

Aha. That explains why this appeared today. I was wondering about that.
— George

> Is the moon there when nobody looks?
> Authors: Guillaume Adenier
> (Submitted on 10 May 2007)
>
> Abstract: In 1981, David Mermin described a cleverly simplified version of Bell’s theorem. It pointed out in a straightforward way that interpreting entanglement from a local realist point of view can be problematic. We propose here an extended version of Mermin’s device that can actually be given a simple local realist interpretation, and we argue that we still have no scientific reason to believe that the moon could possibly not be there when nobody looks.
>
> Comments:
> 11 pages, 8 Figures, 1 Table
> Subjects:
> Quantum Physics (quant-ph)
> Cite as: arXiv:0705.1477v1 [quant-ph]

Hey Chad! Didn’t know you had a blog. I found it from the 2nd page under “Top stories in 24 hours.” I enjoyed the post, I’m taking Quantum Chemistry right now, so I have a light grasp on what you are talking about. I’ll be working with the chemistry and physics departments this summer for research so I’ll see you around.

Expand this. Weave it into a kids’ story for 6-10 year olds. Second book on chemistry from the perspective of physics for the same age group. Then another on math. All can feature your dog. You won’t need tenure to have a career and you’ll do more good for a lot bigger audience than being a professor. You’re on to something. It’s highly needed.

Very interesting Chad and entertaining! Dogs do know this stuff, they just choose not to apply it! 8^) There are some interesting implications here: Those things at absolute zero either exist across all dimensions or none. One might also suppose that black holes do too, as, according to the latest thinking, no information is lost at the event horizon.

Wow – a dog that mis/undertands the quantum world. That’s amazing!
I like reading about physics, although there’s a lot in quantum physics I distrust. This is an informative, and entertaining blog. Well done! The fun aspect makes the learning easier.
Although, thinking about it some more, most if not all pet owners talk to their pets, and there’s no doubt the pets try to communicate back with us. Maybe one day when they can talk, or relay their thoughts to as in another manner, they may actually be able to un-entangle all this quantum stuff for us.

Wow – a dog that mis/undertands the quantum world. That’s amazing!
I like reading about physics, although there’s a lot in quantum physics I distrust. This is an informative, and entertaining blog. Well done!

Books

You've read the blog, now try the books:

Eureka: Discovering Your Inner Scientist will be published in December 2014 by Basic Books. "This fun, diverse, and accessible look at how science works will convert even the biggest science phobe." --Publishers Weekly (starred review) "In writing that is welcoming but not overly bouncy, persuasive in a careful way but also enticing, Orzel reveals the “process of looking at the world, figuring out how things work, testing that knowledge, and sharing it with others.”...With an easy hand, Orzel ties together card games with communicating in the laboratory; playing sports and learning how to test and refine; the details of some hard science—Rutherford’s gold foil, Cavendish’s lamps and magnets—and entertaining stories that disclose the process that leads from observation to colorful narrative." --Kirkus ReviewsGoogle+

How to Teach Relativity to Your Dog is published by Basic Books. "“Unlike quantum physics, which remains bizarre even to experts, much of relativity makes sense. Thus, Einstein’s special relativity merely states that the laws of physics and the speed of light are identical for all observers in smooth motion. This sounds trivial but leads to weird if delightfully comprehensible phenomena, provided someone like Orzel delivers a clear explanation of why.” --Kirkus Reviews "Bravo to both man and dog." The New York Times.

How to Teach Physics to Your Dog is published by Scribner. "It's hard to imagine a better way for the mathematically and scientifically challenged, in particular, to grasp basic quantum physics." -- Booklist "Chad Orzel's How to Teach Physics to Your Dog is an absolutely delightful book on many axes: first, its subject matter, quantum physics, is arguably the most mind-bending scientific subject we have; second, the device of the book -- a quantum physicist, Orzel, explains quantum physics to Emmy, his cheeky German shepherd -- is a hoot, and has the singular advantage of making the mind-bending a little less traumatic when the going gets tough (quantum physics has a certain irreducible complexity that precludes an easy understanding of its implications); finally, third, it is extremely well-written, combining a scientist's rigor and accuracy with a natural raconteur's storytelling skill." -- BoingBoing